VEGETABLE AND FIELD CROPS 



257 



mature, somewhat pink. In these spots pycnidia are 

 visible in abundance, and under favorable conditions the 

 spore masses may be seen 

 issuing from them, even with 

 the naked eye. Upon the 

 leaves similar oval spots, 3-10 

 mm. in diameter, with the 

 pycnidia usually in concentric 

 circles, are very abundant. 

 The lower older leaves are 

 affected first, resulting in 

 their death. The younger 

 leaves die later. Stems are 

 subject to the same attack 

 — first near the ground, later 

 upon all parts; the spots 

 often penetrating through the 

 woody part, thus causing wilt- 

 ing and death of the parts 

 beyond. The stem attack is 

 the most serious form, since 

 it directly causes death to a 

 large part of the plant. This 

 is especially true if the disease 

 be followed by dry weather. 



All forms of the disease 

 tend to decrease the yield just in proportion to their prev- 

 alence. Plants not killed before flowering may develop 

 pods, though of lessened yield. 



Disease upon the pod ma}^ penetrate completely through 

 it and appear upon the opposite side, or more frequently 



Fig. 115. — Pod.s of French June field 

 pea spotted by ascochytose. After 

 van Hook. 



